Fibre Distribution Ltd: FAQ

Fibre patch cables

Why do I need a fibre patch cable?

Whenever you have to connect or join two pieces of Fibre optic equipment together, you will need a Fibre patch cable. It's the same principal as a Cat5 patch cable

Do I need simplex or duplex?

The physical connectors on the equipment you are connecting together will dictate this. For example if your equipment has an SFP (Small Form-factor Pluggable) interface, then these are typically dual or 'duplex' LC type connections.

What connector type do I need?

Again, this will be dictated by the connector type that you are plugging in to. There are several connector types, each with their own physical attributes. Some of them provide a 2.5mm ferrule, such as ST, SC & FC and some provide a 1.25mm ferrule, such as LC & MU
Please check the connector type pictures provided below.

What is the 'ferrule'?

The 'ferrule' is the white ceramic tip that can be seen at the end of the connector, which pushes into the respective socket or bulk-head fitment. The actual Fibre optic cable is embedded in the centre of the ferrule

What length of cable do I need?

This will be dictated by the distance between the two pieces of equipment being connected together. However it is always best to leave extra for any positioning inside racks that might occur. If in doubt, always over estimate if exact lengths cannot be provided.

What is the difference between Multi-mode and Single-mode?

Multi-mode Fibre cable is available with two different 'core' sizes, which are 50 micron or 62.5 micron and they both have the same cladding size, so they are typically shown as '50/125u' and '62.5/125u'. These types of cables were originally produced for deployments over short distances, such as within premises or small campus environments, being used by LED based devices. So predominantly used for much lower speeds, with the distance achievable, degrading as the speed rises. This is due to way light is transmitted from the LED source into the Fibre core, in a kind of 'scatter gun' style.

Single mode cable has a similar physical attribute but with the core size being 9microns, so typically shown as '9/125u'. This type of cable would be used by Laser enabled devices which provide a more 'coherent' light source to fire into the core, such as a rifle would do. Typically used for higher speeds and longer distances

Why are some cables ruggedised?

Where Fibre optic cables need to be deployed under a floor for example, then a more rugged type of cable may be required to prevent any kind of damage to the outer sheath of the cable.
Similarly, if a particularly long Fibre patch cable is required, then being more rugged, may prevent any damaged when it is 'pulled' in to place.

Do fibre optic cables require careful handling?

As the core of a Fibre optic cable is a type of glass, it can be prone to damage if it is bent or crushed too severely. For example, when installing a Cat5 cable into a rack, you might fix it in place with a plastic 'tie-wrap'. These types of fixings can be pulled quite tight and would damage a Fibre optic patch cable if pulled too tightly. When installing into a communications rack or cabinet, they may protrude too far out and be bent by the cabinet door when closed.
If they do become damaged then optical transmission will become impaired.